/*
 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package org.eclipse.imagen.media.codec;

import java.io.Serializable;

/**
 * A class representing a field in a TIFF 6.0 Image File Directory.
 *
 * <p>The TIFF file format is described in more detail in the comments for the TIFFDescriptor class.
 *
 * <p>A field in a TIFF Image File Directory (IFD). A field is defined as a sequence of values of identical data type.
 * TIFF 6.0 defines 12 data types, which are mapped internally onto the Java datatypes byte, int, long, float, and
 * double.
 *
 * <p><b> This class is not a committed part of the JAI API. It may be removed or changed in future releases of JAI.</b>
 *
 * @see org.eclipse.imagen.operator.TIFFDescriptor
 * @see TIFFDirectory
 */
public class TIFFField extends Object implements Comparable, Serializable {

    /** Flag for 8 bit unsigned integers. */
    public static final int TIFF_BYTE = 1;

    /** Flag for null-terminated ASCII strings. */
    public static final int TIFF_ASCII = 2;

    /** Flag for 16 bit unsigned integers. */
    public static final int TIFF_SHORT = 3;

    /** Flag for 32 bit unsigned integers. */
    public static final int TIFF_LONG = 4;

    /** Flag for pairs of 32 bit unsigned integers. */
    public static final int TIFF_RATIONAL = 5;

    /** Flag for 8 bit signed integers. */
    public static final int TIFF_SBYTE = 6;

    /** Flag for 8 bit uninterpreted bytes. */
    public static final int TIFF_UNDEFINED = 7;

    /** Flag for 16 bit signed integers. */
    public static final int TIFF_SSHORT = 8;

    /** Flag for 32 bit signed integers. */
    public static final int TIFF_SLONG = 9;

    /** Flag for pairs of 32 bit signed integers. */
    public static final int TIFF_SRATIONAL = 10;

    /** Flag for 32 bit IEEE floats. */
    public static final int TIFF_FLOAT = 11;

    /** Flag for 64 bit IEEE doubles. */
    public static final int TIFF_DOUBLE = 12;

    /** The tag number. */
    int tag;

    /** The tag type. */
    int type;

    /** The number of data items present in the field. */
    int count;

    /** The field data. */
    Object data;

    /** The default constructor. */
    TIFFField() {}

    /**
     * Constructs a TIFFField with arbitrary data. The data parameter must be an array of a Java type appropriate for
     * the type of the TIFF field. Since there is no available 32-bit unsigned datatype, long is used. The mapping
     * between types is as follows:
     *
     * <table border=1>
     * <tr>
     * <th> TIFF type </th> <th> Java type </th>
     * <tr>
     * <td><tt>TIFF_BYTE</tt></td>      <td><tt>byte</tt></td>
     * <tr>
     * <td><tt>TIFF_ASCII</tt></td>     <td><tt>String</tt></td>
     * <tr>
     * <td><tt>TIFF_SHORT</tt></td>     <td><tt>char</tt></td>
     * <tr>
     * <td><tt>TIFF_LONG</tt></td>      <td><tt>long</tt></td>
     * <tr>
     * <td><tt>TIFF_RATIONAL</tt></td>  <td><tt>long[2]</tt></td>
     * <tr>
     * <td><tt>TIFF_SBYTE</tt></td>     <td><tt>byte</tt></td>
     * <tr>
     * <td><tt>TIFF_UNDEFINED</tt></td> <td><tt>byte</tt></td>
     * <tr>
     * <td><tt>TIFF_SSHORT</tt></td>    <td><tt>short</tt></td>
     * <tr>
     * <td><tt>TIFF_SLONG</tt></td>     <td><tt>int</tt></td>
     * <tr>
     * <td><tt>TIFF_SRATIONAL</tt></td> <td><tt>int[2]</tt></td>
     * <tr>
     * <td><tt>TIFF_FLOAT</tt></td>     <td><tt>float</tt></td>
     * <tr>
     * <td><tt>TIFF_DOUBLE</tt></td>    <td><tt>double</tt></td>
     * </table>
     *
     * <p>Note that the <code>data</code> parameter should always be the actual field value regardless of the number of
     * bytes required for that value. This is the case despite the fact that the TIFF <i>IFD Entry</i> corresponding to
     * the field may actually contain the offset to the field's value rather than the value itself (the latter occurring
     * if and only if the value fits into 4 bytes).
     */
    public TIFFField(int tag, int type, int count, Object data) {
        this.tag = tag;
        this.type = type;
        this.count = count;
        this.data = data;
    }

    /** Returns the tag number, between 0 and 65535. */
    public int getTag() {
        return tag;
    }

    /**
     * Returns the type of the data stored in the field. For a TIFF6.0 file, the value will equal one of the TIFF_
     * constants defined in this class. For future revisions of TIFF, higher values are possible.
     */
    public int getType() {
        return type;
    }

    /** Returns the number of data items present in the field. */
    public int getCount() {
        return count;
    }

    /**
     * Returns the data as an uninterpreted array of bytes. The type of the field must be one of TIFF_BYTE, TIFF_SBYTE,
     * or TIFF_UNDEFINED;
     *
     * <p>For data in TIFF_BYTE format, the application must take care when promoting the data to longer integral types
     * to avoid sign extension.
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_BYTE, TIFF_SBYTE, or TIFF_UNDEFINED.
     */
    public byte[] getAsBytes() {
        return (byte[]) data;
    }

    /**
     * Returns TIFF_SHORT data as an array of chars (unsigned 16-bit integers).
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_SHORT.
     */
    public char[] getAsChars() {
        return (char[]) data;
    }

    /**
     * Returns TIFF_SSHORT data as an array of shorts (signed 16-bit integers).
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_SSHORT.
     */
    public short[] getAsShorts() {
        return (short[]) data;
    }

    /**
     * Returns TIFF_SLONG data as an array of ints (signed 32-bit integers).
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_SLONG.
     */
    public int[] getAsInts() {
        return (int[]) data;
    }

    /**
     * Returns TIFF_LONG data as an array of longs (signed 64-bit integers).
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_LONG.
     */
    public long[] getAsLongs() {
        return (long[]) data;
    }

    /**
     * Returns TIFF_FLOAT data as an array of floats.
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_FLOAT.
     */
    public float[] getAsFloats() {
        return (float[]) data;
    }

    /**
     * Returns TIFF_DOUBLE data as an array of doubles.
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_DOUBLE.
     */
    public double[] getAsDoubles() {
        return (double[]) data;
    }

    /**
     * Returns TIFF_SRATIONAL data as an array of 2-element arrays of ints.
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_SRATIONAL.
     */
    public int[][] getAsSRationals() {
        return (int[][]) data;
    }

    /**
     * Returns TIFF_RATIONAL data as an array of 2-element arrays of longs.
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_RATTIONAL.
     */
    public long[][] getAsRationals() {
        return (long[][]) data;
    }

    /**
     * Returns data in TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED, TIFF_SHORT, TIFF_SSHORT, or TIFF_SLONG format as an int.
     *
     * <p>TIFF_BYTE and TIFF_UNDEFINED data are treated as unsigned; that is, no sign extension will take place and the
     * returned value will be in the range [0, 255]. TIFF_SBYTE data will be returned in the range [-128, 127].
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED,
     * TIFF_SHORT, TIFF_SSHORT, or TIFF_SLONG.
     */
    public int getAsInt(int index) {
        switch (type) {
            case TIFF_BYTE:
            case TIFF_UNDEFINED:
                return ((byte[]) data)[index] & 0xff;
            case TIFF_SBYTE:
                return ((byte[]) data)[index];
            case TIFF_SHORT:
                return ((char[]) data)[index] & 0xffff;
            case TIFF_SSHORT:
                return ((short[]) data)[index];
            case TIFF_SLONG:
                return ((int[]) data)[index];
            default:
                throw new ClassCastException();
        }
    }

    /**
     * Returns data in TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED, TIFF_SHORT, TIFF_SSHORT, TIFF_SLONG, or TIFF_LONG format
     * as a long.
     *
     * <p>TIFF_BYTE and TIFF_UNDEFINED data are treated as unsigned; that is, no sign extension will take place and the
     * returned value will be in the range [0, 255]. TIFF_SBYTE data will be returned in the range [-128, 127].
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED,
     * TIFF_SHORT, TIFF_SSHORT, TIFF_SLONG, or TIFF_LONG.
     */
    public long getAsLong(int index) {
        switch (type) {
            case TIFF_BYTE:
            case TIFF_UNDEFINED:
                return ((byte[]) data)[index] & 0xff;
            case TIFF_SBYTE:
                return ((byte[]) data)[index];
            case TIFF_SHORT:
                return ((char[]) data)[index] & 0xffff;
            case TIFF_SSHORT:
                return ((short[]) data)[index];
            case TIFF_SLONG:
                return ((int[]) data)[index];
            case TIFF_LONG:
                return ((long[]) data)[index];
            default:
                throw new ClassCastException();
        }
    }

    /**
     * Returns data in any numerical format as a float. Data in TIFF_SRATIONAL or TIFF_RATIONAL format are evaluated by
     * dividing the numerator into the denominator using double-precision arithmetic and then truncating to single
     * precision. Data in TIFF_SLONG, TIFF_LONG, or TIFF_DOUBLE format may suffer from truncation.
     *
     * <p>A ClassCastException will be thrown if the field is of type TIFF_UNDEFINED or TIFF_ASCII.
     */
    public float getAsFloat(int index) {
        switch (type) {
            case TIFF_BYTE:
                return ((byte[]) data)[index] & 0xff;
            case TIFF_SBYTE:
                return ((byte[]) data)[index];
            case TIFF_SHORT:
                return ((char[]) data)[index] & 0xffff;
            case TIFF_SSHORT:
                return ((short[]) data)[index];
            case TIFF_SLONG:
                return ((int[]) data)[index];
            case TIFF_LONG:
                return ((long[]) data)[index];
            case TIFF_FLOAT:
                return ((float[]) data)[index];
            case TIFF_DOUBLE:
                return (float) ((double[]) data)[index];
            case TIFF_SRATIONAL:
                int[] ivalue = getAsSRational(index);
                return (float) ((double) ivalue[0] / ivalue[1]);
            case TIFF_RATIONAL:
                long[] lvalue = getAsRational(index);
                return (float) ((double) lvalue[0] / lvalue[1]);
            default:
                throw new ClassCastException();
        }
    }

    /**
     * Returns data in any numerical format as a float. Data in TIFF_SRATIONAL or TIFF_RATIONAL format are evaluated by
     * dividing the numerator into the denominator using double-precision arithmetic.
     *
     * <p>A ClassCastException will be thrown if the field is of type TIFF_UNDEFINED or TIFF_ASCII.
     */
    public double getAsDouble(int index) {
        switch (type) {
            case TIFF_BYTE:
                return ((byte[]) data)[index] & 0xff;
            case TIFF_SBYTE:
                return ((byte[]) data)[index];
            case TIFF_SHORT:
                return ((char[]) data)[index] & 0xffff;
            case TIFF_SSHORT:
                return ((short[]) data)[index];
            case TIFF_SLONG:
                return ((int[]) data)[index];
            case TIFF_LONG:
                return ((long[]) data)[index];
            case TIFF_FLOAT:
                return ((float[]) data)[index];
            case TIFF_DOUBLE:
                return ((double[]) data)[index];
            case TIFF_SRATIONAL:
                int[] ivalue = getAsSRational(index);
                return (double) ivalue[0] / ivalue[1];
            case TIFF_RATIONAL:
                long[] lvalue = getAsRational(index);
                return (double) lvalue[0] / lvalue[1];
            default:
                throw new ClassCastException();
        }
    }

    /**
     * Returns a TIFF_ASCII data item as a String.
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_ASCII.
     */
    public String getAsString(int index) {
        return ((String[]) data)[index];
    }

    /**
     * Returns a TIFF_SRATIONAL data item as a two-element array of ints.
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_SRATIONAL.
     */
    public int[] getAsSRational(int index) {
        return ((int[][]) data)[index];
    }

    /**
     * Returns a TIFF_RATIONAL data item as a two-element array of ints.
     *
     * <p>A ClassCastException will be thrown if the field is not of type TIFF_RATIONAL.
     */
    public long[] getAsRational(int index) {
        return ((long[][]) data)[index];
    }

    /**
     * Compares this <code>TIFFField</code> with another <code>TIFFField</code> by comparing the tags.
     *
     * <p><b>Note: this class has a natural ordering that is inconsistent with <code>equals()</code>.</b>
     *
     * @throws IllegalArgumentException if the parameter is <code>null</code>.
     * @throws ClassCastException if the parameter is not a <code>TIFFField</code>.
     */
    public int compareTo(Object o) {
        if (o == null) {
            throw new IllegalArgumentException();
        }

        int oTag = ((TIFFField) o).getTag();

        if (tag < oTag) {
            return -1;
        } else if (tag > oTag) {
            return 1;
        } else {
            return 0;
        }
    }
}
